Diurnal Variations of NSS and MSA Aerosol at Cape Grim
During ACE-1

We measured nonseasalt sulfate (NSS) and methanesulfonate (MSA) on filters
exposed for three hours each from a tower at Cape Grim during the ACE-1
experiment. Filters simultaneously exposed for 6 hours were used as a
quality control check. We sorted the data to isolate periods of "baseline"
air, meaning that it was not influenced by continental emissions and was
clean remote marine boundary layer air. This data was then examined to
identify diurnal variations from which to derive the formation and removal
rates of sulfur containing particles. Simultaneous Moudi impactor samples
were used to characterize the distribution of each species over the 0.1 to
10 um aerodynamic diameter size range.

We will discuss formation and removal mechanisms and infer oxidation rates
from the observed concentration changes.